What are the symptoms and treatment of hyponatremia (low sodium levels)?

Symptoms and Treatment of Hyponatremia

Hyponatremia symptoms depend on both the absolute sodium level and the rate of development, with acute hyponatremia more likely to cause severe neurological symptoms due to cerebral edema, including delirium, impaired consciousness, ataxia, seizures, coma, and brain herniation. 1

Symptoms of Hyponatremia

Mild to Moderate Symptoms (Sodium 125-134 mEq/L)

• Nausea and vomiting
• Headache
• Weakness
• Mild neurocognitive deficits
• Increased risk of falls and fractures
• Gait disturbances
• Cognitive impairment 1, 2

Severe Symptoms (Sodium <125 mEq/L)

• Delirium
• Confusion
• Impaired consciousness
• Ataxia
• Seizures
• Coma
• Brain herniation (rare but life-threatening) 1, 3

Treatment Approach Based on Volume Status

1. Hypovolemic Hyponatremia

• Initial Treatment: Isotonic (0.9%) saline infusion 1
• Addresses underlying cause of sodium and fluid loss (vomiting, diarrhea, diuretics)
• Volume expansion corrects the stimulus for ADH release

2. Euvolemic Hyponatremia

• Initial Treatment: Fluid restriction (<1-1.5 L/day) 1
• Common causes include SIADH, medications, and endocrine disorders
• For refractory cases, consider:
  • Vasopressin receptor antagonists (tolvaptan) for short-term use (≤30 days) 1, 4
  • Initial dose: 15 mg once daily, maximum dose: 60 mg daily
  • Must be initiated in hospital setting with close monitoring 4

3. Hypervolemic Hyponatremia

• Initial Treatment: Fluid restriction + diuretics 1
• Treat underlying condition (heart failure, cirrhosis, renal disease)
• Salt tablets may be considered in some cases 3

Management of Severe Symptomatic Hyponatremia

For patients with severe symptoms (seizures, coma, respiratory distress):

• Emergency Treatment: 3% hypertonic saline 3
• Goal: Increase serum sodium by 4-6 mEq/L within 1-2 hours to reverse hyponatremic encephalopathy 1, 2
• Critical safety parameter: Do not exceed correction rate of 8-10 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS) 1, 4
• Serum sodium should be monitored every 2-4 hours initially in symptomatic patients 1

Monitoring During Treatment

• Serum electrolytes: Every 2 hours initially for symptomatic patients, then daily until stable 1
• Hemodynamic parameters: Blood pressure and heart rate 1
• Fluid input/output: Careful measurement to guide ongoing therapy 1
• Daily weight: To assess fluid status 1

Important Cautions

• Avoid overly rapid correction (>8 mEq/L in 24 hours) to prevent osmotic demyelination syndrome (ODS) 1, 4
• Patients at higher risk for ODS include those with:
  • Severe malnutrition
  • Alcoholism
  • Advanced liver disease
  • Children (due to larger brain/skull size ratio) 1, 4
• ODS typically presents 2-7 days after rapid sodium correction with initial symptoms such as seizures or encephalopathy, followed by short-term improvement and then clinical deterioration 1
• Avoid fluid restriction during the first 24 hours of tolvaptan therapy to prevent overly rapid correction 4

Special Considerations

• Tolvaptan should only be initiated in a hospital setting where serum sodium can be closely monitored 4
• Tolvaptan should not be used for more than 30 days to minimize risk of liver injury 4
• Untreated or improperly managed hyponatremia is associated with increased mortality, decreased quality of life, and higher risk of complications 1
• Exercise-associated hyponatremia requires different management, including education about proper hydration during exercise 1

By following this structured approach based on volume status and symptom severity, clinicians can effectively manage hyponatremia while minimizing the risk of complications.